Internal combustion engines combust a fuel and air mixture within cylinders driving pistons to produce drive torque. Engine start-up is induced based on an operator input. For example, an engine starting system cranks the engine and initiates the combustion process based on the operator turning an ignition switch to a start position or depressing a start button. Traditional engine starting systems include a starter motor that selectively drives a crankshaft. More specifically, a pinion gear of the starter motor is movable between an engaged position and a disengaged position relative to a flywheel ring gear.
Temporary engine shut-off at vehicle stop is implemented to reduce fuel consumption. Many configurations have been proposed to accomplish a prompt and low noise restart of the engine at the first indication of an acceleration request from the operator. An acceleration request can be indicated by the driver releasing pressure on a brake pedal and/or depressing an accelerator pedal. Most arrangements use complicated and expensive electric devices to accomplish the start-stop task while meeting noise, vibration and harshness (NVH) and response requirements.
Start-stop configurations using traditional starter motors and drive gear actuation are too noisy for a seamless and pleasing engine start. For example, noise from these systems emanates from a starter pinion solenoid, which moves the pinion gear between the engaged and disengaged positions. More specifically, an abrupt change in armature velocity occurs as the starter pinion solenoid makes contact with its stop.